The present invention relates to a tracking system for sports and more particularly to a tracking system for a plurality of sports players positioned on a pitch or similar area. The system can also comprise tracking of other objects such as horses on a track or racing cars, sailing boats, etc.
The present invention is to be marketed under the name SporTrack is a tracking system that measures the location of players and other objects on the field, with high accuracy and video update rates. The system of the present invention is able to track 100 players or more, simultaneously, in real-time for long periods of time.
The system of the present invention is a cooperative tracking system, designed to track multiple cooperative targets within a given field in real-time with high precision and extremely high update rate. The system is based on state of the art microwave modules and advanced tracking algorithms, to achieve an accurate, independent player location, in every video frame. Synchronized to a calibrated video camera, the system gives the exact location of each player on the screen, allowing instant digital and virtual replay, many different statistics and more. Current microwave technology allows a low power, lightweight tracking system due to precise digital components such as direct digital synthesizer (DDS), high frequency A/D converters and DSPs. The system""s operate at low power (much lower than any ordinary cellular phone) and carefully chosen operating frequencies, assures safe operation in any human or EMI environment and conforms with the strictest international and American standards.
The tracking system will track a player, within the designated field, who is wearing a miniature ID tag. This tag, which may be smaller than a credit card and lighter than 20 grams, is actually a transponder that reflects the signal sent from the transmitter and identifies each player in his exact location. This procedure is done simultaneously for all players, and is preferably repeated every video frame. The tracking of each player is independent, and a single player can be tracked as well as 50 players, all on the same field.
SporTrack utilizes some of the latest microwave and DSP technologies. The main building block is an advanced, low power, spread spectrum radar that incorporates the advantages of MMIC (Miniature Microwave Integrated Circuits) components and power signal processors.
The use of these microwave components allows the system not only to be small and lightweight, but also inexpensive. Due to the fact that the system is designed to operate at short distances, and the use of spread spectrum techniques, the average and peak transmitting power is so low, that it is literally unaffected by EMI/RFI and completely safe to humans. In fact, the carefully chosen transmitting frequencies and output power are well below any international radiation standards including the strictest FCC recommendations in the USA. The small transponders worn by the player are similar to the xe2x80x9csmart cardsxe2x80x9d that are developed today around the world for many different applications. The transponders small volume and weight make it almost unnoticeable to the player that can keep playing exactly as before.
The high update rate and the use of advanced waveforms being the need to process large amounts of data in a very short time. This is the reason that the main processor was developed with the Analogue Device SHARC processor, a powerful DSP which is widely used all over the world. The processor handles long FFTs and IFFTs as well as tailor made CFAR (Constant False Alarm Rate) algorithms. The processor and these high rate algorithms are developed together to achieve the high efficiency needed for real-time operation. Other, more situation dependent algorithms, such as the various stages of the tracking procedure are processed in another DSP, which is also a part of the main processor.
Much attention is given to the integration of the tracking system with the video cameras and the graphics computer. Successful integration means a synchronized system, enabling instant transformation from field coordinates to pixel location in every single frame.
TV broadcasts of sports events use different graphic effects such as highlighting a player, marking his trail, measuring his position, and more. In order to display the graphics on the screen in real-time, or instant replay, the object""s position must be known. Current methods of tracking allow image tracking but have the disadvantage of working off-line and most methods lack robustness. Thus, it takes a long time to track a player from a video clip, and the user must supervise the process. This prevents instant replays with graphic effects, of interesting plays in a live broadcast.
GB A 2298098 discloses a tracking system for tracking objects in an area comprising first and second microwave antennas, one antenna comprising a microwave transmitter and one a receiver and including coded transponders carried by one or more of the objects to be tracked in the area the receiver receiving and processing coded signals for calculating the position and identity of each object.
FR A 2711069 discloses a system for tracking players on a sports field using a plurality of radio transponders.
It is an object of the present invention to provide a system that will track the objects automatically with high precision and in real-time.
The present invention therefore provides a tracking system for tracking players or objects on a sports field, said system comprising a first and a second microwave antenna, one antenna comprising a microwave transmitter and a receiver and the other only a receiver and including one or more coded transponders respectively carried by one or more players or objects on said field, electronic receivers comprising electron processing circuitry connected to receive signals from said transponders received at both said first and second antennas to calculate the position and identity of each player on said field, characterised in that each transponder is unique and comprises means for receiving a microwave signal at a defined frequency from an antenna, means for shifting the frequency of said received signal by a unique frequency and means for transmitting said shifted frequency signal back to the antenna.
Preferably in the processing circuitry of each receiver means are provided for sorting incoming frequency signals according to their various shifts and also for determining the range of each shifted signal according to the time difference between a transmitted signal and each shifted received signal.
Preferably each player is provided with a pair of transponders of different frequency shift and the receiver circuitry comprises means for recording the frequency shift identity of both of the transponders for each player and further comprises means for decoding the output of each pair of transponders to provide the direction of movement of a player.